Field of the Invention
The invention generally relates to recombinant vectors for use in cancer therapy and/or diagnostics. In particular, the invention provides vectors in which expression of one or more elements (e.g. genes required for viral replication, detectable imaging agents, therapeutic agents, etc.) is driven by an mda-9/syntenin promoter in a cancer- and/or metastasis-specific manner.
Background of the Invention
Melanoma differentiation associated gene-9/Syntenin (mda-9/syntenin) was originally cloned from metastatic human melanoma cells induced to terminally differentiate by treatment with recombinant human fibroblast interferon plus the protein kinase C activating agent mezerein (Jiang and Fisher, 1993; Lin, et al., 1996, 1998; Sarkar, et al., 2004). Expression of mda-9 is biphasic, with an early peaking (8 to 12 hr) in activity and then a decrease over time (24 to 72 hr). This gene was subsequently cloned as a syndecan interacting protein and named syntenin (Grootjans, et al., 1997). MDA-9/syntenin is a PDL domain containing adapter protein (FIG. 1A) that plays a central role in regulating cell-cell and cell-matrix adhesion. MDA-9/syntenin transduces signals from the cell-surface to the interior through its interaction with a plethora of additional proteins and actively participates in intracellular trafficking, cell-surface targeting, synaptic transmission, and axonal outgrowth (Grootjans, et al., 1997). Recent studies have documented a seminal role of mda-9/syntenin in cancer metastasis (Boukerche, et al., 2008; Das, et al., 2012a, 2013). Overexpression of mda-9/syntenin has been identified in metastatic melanoma, breast and gastric cancer cells in comparison to the primary tumor or poorly metastatic counterparts (Das, et al., 2012a; Qian, et al., 2013). Data available from the website located at cancergenome.nih.gov documents overexpression of mda-9/syntenin in additional cancers such as glioblastoma multiforme, squamous cell carcinoma of the lungs and serous cystadenocarcinoma of the ovary and clear cell carcinoma of the kidneys. Other studies also identify overexpression of mda-9/syntenin in human Hepatocellular Carcinoma (HCC) compared to the normal liver, in bladder cancer vs. normal bladder and in glioblastoma multiforme (GBM) vs. normal brain (Dasgupta, et al., 2013; Kegelman et al., 2014). Forced overexpression of mda-9/syntenin results in increased migration of non-metastatic cancer cells which correlates with a more polarized distribution of F-actin and increased pseudopodia formation. MDA-9/syntenin promotes invasion and metastasis through interactions with c-Src and promotes the formation of an active FAK/c-Src signaling complex leading to NE-κB and matrix metalloproteinase (MMP) activation (Boukerche, et al., 2010) (FIG. 1B). Additionally overexpression of mda-9/syntenin leads to activation of Ras, Rho, Rac, PI3K/Akt and MAPK signaling.
Adaptor molecules, which contain protein-protein interaction domains, are involved in the assembly of multimeric complexes that play an essential role in modulating signal transduction from the extracellular environment to the intracellular milieu by virtue of their association with key regulatory molecules (Das, et al., 2012a). PDZ domains (an acronym for three proteins, postsynaptic density protein PSD95/SAP90, drosophila tumor suppressor DLGA, and tight junction protein ZO-1 containing proteins) are present in a diverse group of over 150 proteins that control a plethora of physiologic processes. MDA-9/syntenin has two PDZ domains: PDZ-1 (a.a.110-193) and PDZ-2 (a.a.194-274) (FIG. 1A). Both PDZ domains are critically involved in metastasis, since deletion mutants (either one of the two PDZ domains) of MDA-9/syntenin significantly reduced lung metastases of melanoma cells compared with the cells transfected with wild type MDA-9/syntenin. The interaction of c-Src with MDA-9/syntenin is mediated by carboxylate-binding loop of PDZ-2 (Boukerche, et al., 2010). However, PDZ-1 also plays a critical role in binding by promoting the proper folding of PDZ-2 that assembles MDA-9/syntenin into a multimeric complex resulting in a more stable functional unit. MDA-9/syntenin through its interaction with itself and with c-Src enables c-Src/FAK signaling complexes clustered at high concentrations on the plasma membrane to amplify signaling through FAK intermolecular autophosphorylation. These events lead to enhanced cell motility, invasion, and metastasis as confirmed by overexpression and knockdown studies (Boukerche, et al., 2005; Boukerche, et al., 2010). Additionally, MDA-9/syntenin can directly regulate new blood vessel formation, angiogenesis (Das, et al., 2013).
Cancer (malignant neoplasia) is a broad group of diseases involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, which may invade nearby parts of the body. The cancer may also spread to more distant parts of the body through the lymphatic system or bloodstream (metastasis). Cancer is usually treated with one or a combination of chemotherapy, radiation therapy and surgery. While treatment methods have advanced significantly, the outcomes for particular cancers is still not optimal, current treatments often have very harsh side effects, and if the cancer is not detected early, the chances of survival are greatly reduced. Metastatic cancer is particularly difficult to locate and treat.
Cancer can be detected in a number of ways, including the presence of certain signs and symptoms, various screening tests, and/or medical imaging. While detection methods have also improved markedly over the years, there is still a need in the art to detect and treat cancers earlier and more effectively. In particular, there is a great need to develop targeted therapeutic and imaging methodology so that e.g. tumors and metastatic cancer cells can be located and eliminated with a minimum of damage to healthy tissue. To that end, it would be advantageous to have available additional cancer-selective and/or cancer-specific promoters in order to develop improved therapeutic and diagnostic constructs for use in the detection and treatment of cancers.